Returns 401 when unauthorized project access occurs

Throwing wsme based exceptions out of non-wsme context causes api server
to return 500 since the exception goes uncaught. Instead return
http response with error code 401 to return to client safely

Change-Id: Ifb753581e392ea7961b976bc97ee2348feb6825c
Closes-Bug: 1365770
Merge "Returns 401 when unauthorized project access occurs"